Ripper devices are mounted on tractors and are pulled thereby to break a path through the ground and fracture the ground to a certain depth. Such devices are generally in the form of an upstanding shank having a chisel shaped blade at its lower end and attached at its upper end to the tractor through a series of links forming an articulated tool mount. Power cylinders are operatively connected to the tool mount to change the attitude and depth of penetration of the ripper blade. In operation, the ripper blade is elevated to a position out of the ground until the subject ground site is arrived at. At the proper site, the tractor moves forward while the ripper tool is depressed into the ground in a penetrating mode until it reaches the working or ripping depth. Experience has shown that the angle at which the ripper blade is positioned with respect to the path of the tractor affects the efficiency and life of the ripper blade. It has been determined that the ripper blade performs best if it is at a steep angle of attack when moving downward to the ripping depth in the penetrating mode. It has also been determined that the life of the blade is increased if the blade is at a shallow angle of attack when in the ripping or working mode of operation. Thus, it is desirable to change the angle of attack of the ripper blade between the penetrating mode and the ripping mode.
Generally, the depth at which this change is made is derived empirically for a given ground structure. Similarly, the most desirable attitude angles of the ripper blade in the penetrating and ripping modes may change, depending on the particular ground structure.
When a number of tractor operators are engaged in working the same ground plot, it is desirable that they all be working under the same attitude and depth parameters. These parameters are chosen by a supervising operator or "dirt boss". Heretofore, the various operators had to visually rely on the relative position of the ripper shank, tool mount and tractor to determine the depth and attitude of the ripper blade. Obviously, this provided varying degrees of accuracy in reaching and maintaining the prescribed depth and pitch for the ripper blade.
It is in the course of the above that this invention is concerned, wherein the expertise of an experienced supervisor may be used to best position the ripper blade for individual tractors by preselecting settings on an automatic control device and where the preselected conditions will be carried out without the conscious effort of the tractor operator.